Aliens vs Devils
by Vaenny
Summary: Zack is a person with special circumstances. Other than being a predalien raised by the demon Azazel, he is constantly surrounded by dangerous beings who are out to get him, both in and out of this world. And as such, his entire existence has created a war between the extraterrestrial and the supernatural. How will Zack act in this war of the worlds?
1. Prologue

Prologue

At first glance, Zachery Orion seems like a normal human being, living a normal human life. He's not so social, not good at school, and totally fails when it comes to love. But underneath that ordinary face lies a dark and horrible fate.

In truth, he is actually a predalien in disguise. He lost his parents at a young age by Xenomorphs and was made a slave. Then he was experimented on to kill all the devils that step into the face of the earth. Inside his body were now traces of predators, xenomorphs and anti-symbiotes. With all that, he would have been the strongest being in the whole universe... perhaps too strong... After unleashing his full power unto the devils, he passed out and was found by Azael, who trained him for 3 years in preparation for "the day".

And this is where our story begins...


	2. Chapter 1

Chapter 1

"RIIIIIIING!"

My infernal alarm clock woke me up once again. You'd think that despite being half predalien, this wouldn't bother me much. Perhaps I was more human than I thought. I slowly rose up from my bed and look into the mirror. It was the same face as a human's, but slightly pale. So far, so good. Then, as I blinked, I saw my reflection of that of my "other half". One more blink woke me up from reality. Perhaps there was no escaping the horrible reality of what I really am.

"No turning back, huh..."

After evaluating myself, I went on to change into my school uniform and went downstairs to get something to eat. I opened the fridge and nothing caught my eye.

"No good..."

Despite the fridge being full of food, I didn't have the desire to eat it. Instead, I had this urge to eat something else... But seeing as I wasn't hungry in the first place, I decided to skip breakfast. Before I head off to school, I approached the door of my basement and said:

"I'm going now!"

You might be wondering what I'm keeping in the basement. Well, let's just say... it's my Plan B. After bidding them goodbye, I left the house and proceeded to walk to school. On the way, I spotted a similar face from the other side of the road. There she was: Raynelle. I couldn't believe that she had moved on from me so fast. Now she had her eyes on a perverted guy named Issei. I had no idea what she was up to, but I know it wasn't good. I decided to ignore them and walked straight because I could sense that someone was following me. It felt like a facehugger, but with a different aura.

Anyway, I rushed to school and went straight to my classroom. That way, not just anyone would be able to enter in such a crowded place. My classmates greeted me as usual and I did the same. Afterwards, I went to my seat and stared into the window. Outside, I saw the track and field club running around the field. It was a bit early for training, but it must've been fine with them since they haven't stopped once.

"Maybe I should join them..."

At that very moment, someone appeared in front of the female members and cuffed his hands as if trying to squeeze something. The female members then proceeded to kick and step on him as he was a well-known pervert.

"Die, you pervert!"

"Gross!"

The man they were stepping on was none other that Hyoudou Issei, a school pervert. I haven't the slightest idea why Raynelle found him attractive. It's true that I sense a dark aura around him, almost like a dragon's, but he was more human than anything else. His actions, at least, prove that he's nothing more than that.

Time passed by so quickly. Before I knew it, classes were over. There was really no point in me studying proper human knowledge, but if I wanted to be a normal teenager then I had to participate in such sessions. As I left the school premises, I saw Raynelle once again, walking together with a man I didn't know. This is why I found humans cruel: they cater to their selfish needs before others. I avoided any contact with them and walked straight home, where, I would prepare my hunt for tonight.

And when daylight ended, I set out to hunt, carrying my Yautja weapons: My combi Stick, Plasma bolt, Netgun, Plasma caster and wrist blades, all shrouded in my long coat. Leaping from one building to another, I searched for any prey that would get caught in my vision. And alas, I saw a shadow of a devil's near a streetlight. Carefully, I approached the shadow, but it disappeared all of a sudden.

"Where'd it go?"

Then suddenly, I heard voices coming from the opposite direction. I decided to hide in one of the bushes and stayed there. To my surprise, I saw the perverted Issei walking together with a beautiful girl. And it wasn't just any girl: It was Raynelle, but it didn't feel like it was her. It felt more like a doppelganger or something. They stopped at the nearest fountain, at the center of the park.

"What is she up to...?"

sneakily, I eavesdropped on their conversation:

"What's wrong?" Issei asked.

Raynelle tugged her skirt and said, "To tell you the truth, I'm actually..."

At that moment, I saw a burst of aura emit from her body. Without hesitation, I interrupted their conversation and jumped in to save Issei. I tackled the mimic and took out my combi stick.

"Stop right there, fallen angel!"

"Oh, my cover's been blown?" she responded.

Meanwhile, Issei was sitting on the floor, confused and panicked. And once the impostor noticed that, she crossed her arms, giving emphasis to her chest, and declared, "Since you know what I am then I have to kill you as well"

Could it be true? Was the girl in front of me really a fallen angel ? Was this the being that master warned me about? Either way, she tried to kill a human, and I couldn't let that pass. The battle between Zack and the supernatural has begun!


	3. Chapter 2

Chapter 2

In front of me was a fallen angel taking in the appearance of Raynelle. Despite looking the same, their personalities were too different. That itself was enough reason for me to kill her. And so I held my combi stick and plunged it into her, but she managed to dodge it easily. I continued plunging the tip but none of it were hitting her. And so I changed my tactic. I threw my combi stick in the air and used my netgun to capture her. But again, to no avail.

"Is that the best you can do?" she commented.

At that moment, the spear I threw landed right back down, damaging her right arm.

"Tch... you're good..." she murmured.

It was an easy win. It didn't even take two seconds. I reclaimed my combi stick and pointed it at her.

"I'll ask again: Who are you? And what do you want with Issei?"

"That collection of weapons..." she reacted, "Is that what I think it is?"

Confused and shocked, Issei shouted, "W-what he heck is going on here?!"

At that moment, the fallen angel, with her right hand behind her, threw a spear of light to Issei, piercing straight into his torso. Then as my attention was on the dying Issei, she managed to escape my grasp. And just like that, she was gone.

"Dammit!"

I quickly rushed to Issei, but it was too late. He no longer had a pulse. Then suddenly, I felt another person's presence from not so far away. We were being watched. I had to aid him, but I didn't wanna risk being seen as a murderer, especially when I'm finally living a peaceful life. So as cruel as it might be, I left the dead body alone and went back home.

The next day, while eating breakfast, I pondered on how to explain the circumstances to Issei's parents.

"What should I say...? Maybe I could run to their house, all panicked, and tell them that I heard of his death from someone. But that would sound suspicious, coming from someone who's not even close to him. Maybe I can leave a note? But that'd look like a death threat and I'm targeting them next... Oooh...!"

Tapping my feet repeatedly, I couldn't get the problem out of my head. And it remained until I got to school. When I got to my classroom, I went straight to my seat, pondering even more. Then, from outside, I heard someone shout:

"OPPAI!"

Issei was alive and well? How could it be? I could've sworn that he died that night. Yet why is he acting like his usual self? Don't tell me: someone resurrected him! That was the only thing that came to mind. But if that's the case, then who could've done it? It couldn't have been the fallen angel. Perhaps it was the person who was watching us yesterday. Come to think of it, the aura of that stalker had that of a devil's.

When I finally figured it out, I approached the one person who most likely knew what happened, and perhaps the cause of all this: Rias Gremory. I heard that name from Azazel, and just when I finished my training, I decided to choose the school she was going to in case she was up to no good. So far, nothing's happened yet, but I had a feeling that something was about to.

I entered Rias' clubroom and to my surprise, saw her comfortably seated in the sofa as if she was expecting me.

"What are you up to?"

"What do you-"

"Why is Hyoudou Issei still alive?!"

I clenched my fists and continued, "I saw it all... he was dead... But right now, he's walking around like nothing happened!"

Then when I took a step forward, Koneko, one of her servants, stood in between us.

"It's alright, Koneko." Rias said.

And so she followed her master's order and left us alone. Then Rias stood up and explained everything:

"Since you know about our war with the angels and fallen angels, I'll skip to what I did to Issei. You see, I'm lacking servants to fight with me, and I needed someone who could fulfill that role. There, I found, Hyoudou Issei. At first, he might seem like an ordinary boy, but he has potential to be one of my servants. However, in order to transform him into one, he had to die and be reincarnated."

"So the fallen angel's attack on Issei was all you doing?"

"Not exactly." she replied, "I think they somehow knew what I was up to and wanted to put a stop to it."

"But it backfired, right?"

"Exactly."

So it was all her doing. He used Issei to her own advantage. I guess it was a good thing because he could finally protect himself from fallen angels.

"By the way..." Rias said, "I've known you for quite some time, but I hardly know anything about you..."

Did she notice? Was my cover blown? It looked like it because she was calling Koneko back in.

"I've only heard rumors about it, but could you be... the apex-"

At that moment, I saw myself to the door. I couldn't risk my identity being exposed. Fighting her would result to nothing.

"Just keep an eye on him, and forget that we ever met."

"Good choice." she replied.

And so, I left the clubroom and went back to class. A couple of pointless class lectures later, we were dismissed. I went straight home, planning on my next hunt tonight. However, when I got to the door, it opened by itself. And on the other side was...

"Welcome home!"

Kuroka.

* * *

Hey guys! Yes, it's me, the author. I forgot to mention this in the first chapter, but this crossover is actually a collab between me and Lewamus Prime. At first, I was reluctant to make it with him. But when I heard that it was gonna take place in highschool DxD's universe, I thought, "why not?". This took a month of planning before the actual publication came out, so I hope all our efforts paid off. Hope you enjoyed this chapter and the many chapters to come!


	4. Chapter 3

Chapter 3

"Welcome home!" Kuroka greeted.

"W-what are you doing in my house?! How did you even get in?!"

This girl. She's nothing but trouble. I was sure that she was up to something, but before I could ask, she cut me off.

"Ah! The curry!" she exclaimed as she ran back to the kitchen.

"Wait, you were cooking?!"

Fast forward an hour later, Kuroka and I were seated on the dinner table, eating the curry that she cooked for us.

"Thank you for the food!" she said as she took a spoonful in her mouth.

"Slow down, will you?"

I still couldn't believe that I was going out with her. Sure, she's cute, but she gets annoying at times. There was this one time where she stuck a lollipop on my hair only to realize it's been there for 5 hours. As payback, I swapped her foundation with milk and her face got sticky the whole day. But despite all that, she still chose to be with me even after I revealed to her who I truly was.

"Speaking of which..." she asked, "Have you met with Raynelle recently?"

I wanted to respond with a no, but I couldn't stop but think that the fallen angel from yesterday might be related to Raynelle somehow. Instead, I asked her if she knew any stray fallen angels walking around town recently. After all, she was a fallen angel.

"Why the sudden interest?" she asked.

"It's a secret."

"Aww, you're so mean!"

I couldn't risk her knowing about it. What if they went after her because I told her? There was no way I could tell her.

"Well, I'm in a good mood today. Sure!" she answered.

She was so understanding. I guess that's also one thing I liked about her.

"Recently, there have been an outbreak of fallen angels turning humans into their pawns."

"Really?"

If that were the case, then it made sense that Rias made Issei one of her pawns. With so many fallen angels running out and about, she needed more people to protect her. But then... what about the mimic Raynelle? Was she also planning on taking Issei to her side?

"This war..." she added, "When will it end...?"

She cuffed her hands and placed it near her chest. She was tired of all the fighting. I wish I could say the same. But all I could do was comfort her and assured to her that it will end.

"I just want everything to go back to the way it was..."

I went to her side and hugged her from behind. This war was affecting her so much. And so I vowed to stop the war myself, so Kuroka, Rias and Raynare didn't have to go through so much pain again.

After dinner, I once again prepared my equipment for the hunt. I left the house and leapt to the top of the nearest building. Then suddenly, I felt a familiar presence nearby. Sneakily, I went to where the presence was. And, to my surprise, I saw Raynare in front of Issei's house.

"Y-you're-!"

"Ah! You caught up!" she said.

Raynere: Raynelle's twin sister. She's a fallen angel, much like her sister. However, her personality was completely different. While Raynelle was deceptive and cruel, Raynere was the honest and forgiving one. Despite that, I still couldn't put my trust in her. She was a fallen angel, after all. What was she doing in front of Issei's house?

I took out my combi stick and netgun and prepared myself for battle.

"Relax, I don't intend to do anything." she said.

"Then why are you here?!"

Kuroka told me earlier of the stray fallen angels running rampant in the city. With that logic, I concluded that she might be one of them. However, when she stated her reason, I began to doubt my logic.

"I'm waiting for someone." she said.

"For who?"

"Raynelle." she replied, "Because she's so fond of Issei, I thought she might sneak inside the house. When that time comes, I can finally put a stop to all her despicable acts."

After hearing that, I was willing to offer her a hand.

"We are after the same target."

"I don't think I can trust you." she answered.

"Why not?"

"For one, I'm a fallen angel too." she said, "A hunter like you could easily betray me."

She had a point. I was on the hunt for stray fallen angels. But the circumstances demanded an exception. Besides, she wasn't a stray to begin with. She had stayed in this town for almost a year. Strays don't stay in one place for too long. I knew this from previous experience. With that in mind, I told her that I wouldn't do things behind her back.

"Promise?" she asked.

"Yeah, yeah, I promise."

and with that, I gained another ally in the search for Raynelle.

* * *

Hey guys! So some of you might have already noticed the harem tone that the story possessed. Well, DxD is technically a harem and Predator does have his harem of victims!

*ba dum tss*

Okay, I'll shut up now...

Anyway, I hope you liked this chapter! Next chapter comes out in a week, so look forward to that!


	5. Chapter 4

Chapter 4

The sunlight was once again blinding my eyes, but for a different reason. The fountain water reflected the sunlight and into my eyes. Perhaps waiting in front of the fountain was a bad idea. And as I waited there, I saw Raynere from afar.

"Heeey!" she shouted.

Let me explain why I'm in the park right now. After Raynare and I met in front of Issei's house, she suggested that we meet again the next had to come up with a plan on how to capture her twin sister.

 _"If she finds out that I'm working with a hunter like you, she'd approach me and ask why I teamed up with you. And when that happens, that's when we capture her!"_

 _"You think that will work?"_

 _"Of course! I know my sister like the back of my hand!"_

The plan sounded fishy, but it seemed possible. All we had to do was meet each other somewhere public, where she can see us out in the open, and wait for her to arrive. However, I didn't think Raynare would take this pretend date seriously. She dressed up in a white tank top and jean shorts with a coat tied to her waist. What's more is that she had makeup on. She was not the Raynare I used to know.

I stood up and asked about her appearance.

"This isn't an actual date, you know?"

"I know!" she said, "but we have to make sure that Raynelle thinks we're on one or else she won't interrupt."

Despite it being a weird plan, we had no other choice. She said that Raynelle easily gets jealous whenever her twin gets something she doesn't have. And so, we went around town, pretending to be dating. We went to watch a sci-fi horror movie which I found funny rather than scary. The way they depicted aliens were so wrong. I guess humans still haven't seen actual extraterrestrial beings yet.

After watching the movie, we went to the shopping center to get something to eat. I was fine with eating anything, but curry was the last thing in my mind. Nevertheless, Raynare wanted curry, so we ate at a restaurant that served extra spicy curry. For some reason, Raynare loved spicy things. It was one of the things I didn't know about her until now.

After eating, we went back to the park and waited for Raynelle to arrive. Spending so much time together, there was no way she would let go of this situation. Also, there were very few people already, so if anything would happen, there won't be that many casualties. Then again, she might have known about our plan beforehand and don't plan on arriving.

Fortunately, she came anyway. She found us from afar and said, "What do you think you're doing, going out with the enemy?!"

Then as she got closer, I took out my portable netgun and shot it without her noticing. Before she could dodge it, Raynare tackled her down to make sure she would get caught in it. And just like that, we succeeded in capturing Raynelle, and it was easier than I thought.

"Good job."

"Thanks!" Raynare replied, "I knew my sister would be vulnerable when she's jealous. She always let her guard down every time something nice happened to me."

But in the midst of our victory, a burst of despair suddenly rose. All of a sudden, Raynelle started uttering something.

"..."

I leaned in closer and found out that she was speaking... in the Xenomorph language! How does she know that?! Were the Xenomorphs connected to the fallen angels too? Was there more to this war than meets the eye?!

* * *

Hey guys! So I'm giving out this story for adoption. Turns out, I can't write two fanfictions at a time. I could, but not this year. My schedule's become very hectic and thus can't write every week anymore. Of course, I don't want Lewamus Prime's story to go to waste, so I'm asking anyone out there who wishes to continue this story to send me a PM and we can talk there. Again, I'm very sorry about this, I hope you understand. But until someone picks up this fanfic, this story will remain unfinished.

Again, please PM me if interested. Thank you very much!


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